/* GNU/Linux/Nios II specific low level interface, for the remote server for

GDB.

Copyright (C) 2008-2016 Free Software Foundation, Inc.

Contributed by Mentor Graphics, Inc.

This file is part of GDB.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 3 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program. If not, see <http://www.gnu.org/licenses/>. */

#include "server.h"

#include "linux-low.h"

#include "elf/common.h"

#include "nat/gdb_ptrace.h"

#include <endian.h>

#include "gdb_proc_service.h"

#include <asm/ptrace.h>

#ifndef PTRACE_GET_THREAD_AREA

#define PTRACE_GET_THREAD_AREA 25

#endif

/* The following definition must agree with the number of registers

defined in "struct user_regs" in GLIBC

(sysdeps/unix/sysv/linux/nios2/sys/user.h), and also with

NIOS2_NUM_REGS in GDB proper. */

#define nios2_num_regs 49

/* Defined in auto-generated file nios2-linux.c. */

void init_registers_nios2_linux (void);

extern const struct target_desc *tdesc_nios2_linux;

/* This union is used to convert between int and byte buffer

representations of register contents. */

union nios2_register

{

unsigned char buf[4];

int reg32;

};

/* Return the ptrace ``address'' of register REGNO. */

static int nios2_regmap[] = {

-1, 1, 2, 3, 4, 5, 6, 7,

8, 9, 10, 11, 12, 13, 14, 15,

16, 17, 18, 19, 20, 21, 22, 23,

24, 25, 26, 27, 28, 29, 30, 31,

32, 33, 34, 35, 36, 37, 38, 39,

40, 41, 42, 43, 44, 45, 46, 47,

48,

0

};

/* Implement the arch_setup linux_target_ops method. */

static void

nios2_arch_setup (void)

{

current_process ()->tdesc = tdesc_nios2_linux;

}

/* Implement the cannot_fetch_register linux_target_ops method. */

static int

nios2_cannot_fetch_register (int regno)

{

if (nios2_regmap[regno] == -1)

return 1;

return 0;

}

/* Implement the cannot_store_register linux_target_ops method. */

static int

nios2_cannot_store_register (int regno)

{

if (nios2_regmap[regno] == -1)

return 1;

return 0;

}

/* Breakpoint support. Also see comments on nios2_breakpoint_from_pc

in nios2-tdep.c. */

#if defined(__nios2_arch__) && __nios2_arch__ == 2

#define NIOS2_BREAKPOINT 0xb7fd0020

#define CDX_BREAKPOINT 0xd7c9

#else

#define NIOS2_BREAKPOINT 0x003b6ffa

#endif

/* We only register the 4-byte breakpoint, even on R2 targets which also

support 2-byte breakpoints. Since there is no supports_z_point_type

function provided, gdbserver never inserts software breakpoints itself

and instead relies on GDB to insert the breakpoint of the correct length

via a memory write. */

static const unsigned int nios2_breakpoint = NIOS2_BREAKPOINT;

#define nios2_breakpoint_len 4

/* Implementation of linux_target_ops method "sw_breakpoint_from_kind". */

static const gdb_byte *

nios2_sw_breakpoint_from_kind (int kind, int *size)

{

*size = nios2_breakpoint_len;

return (const gdb_byte *) &nios2_breakpoint;

}

/* Implement the breakpoint_at linux_target_ops method. */

static int

nios2_breakpoint_at (CORE_ADDR where)

{

unsigned int insn;

/* For R2, first check for the 2-byte CDX trap.n breakpoint encoding. */

#if defined(__nios2_arch__) && __nios2_arch__ == 2

(*the_target->read_memory) (where, (unsigned char *) &insn, 2);

if (insn == CDX_BREAKPOINT)

return 1;

#endif

(*the_target->read_memory) (where, (unsigned char *) &insn, 4);

if (insn == nios2_breakpoint)

return 1;

return 0;

}

/* Fetch the thread-local storage pointer for libthread_db. */

ps_err_e

ps_get_thread_area (struct ps_prochandle *ph,

lwpid_t lwpid, int idx, void **base)

{

if (ptrace (PTRACE_GET_THREAD_AREA, lwpid, NULL, base) != 0)

return PS_ERR;

/* IDX is the bias from the thread pointer to the beginning of the

thread descriptor. It has to be subtracted due to implementation

quirks in libthread_db. */

*base = (void *) ((char *) *base - idx);

return PS_OK;

}

/* Helper functions to collect/supply a single register REGNO. */

static void

nios2_collect_register (struct regcache *regcache, int regno,

union nios2_register *reg)

{

union nios2_register tmp_reg;

collect_register (regcache, regno, &tmp_reg.reg32);

reg->reg32 = tmp_reg.reg32;

}

static void

nios2_supply_register (struct regcache *regcache, int regno,

const union nios2_register *reg)

{

supply_register (regcache, regno, reg->buf);

}

/* We have only a single register set on Nios II. */

static void

nios2_fill_gregset (struct regcache *regcache, void *buf)

{

union nios2_register *regset = (union nios2_register *) buf;

int i;

for (i = 1; i < nios2_num_regs; i++)

nios2_collect_register (regcache, i, regset + i);

}

static void

nios2_store_gregset (struct regcache *regcache, const void *buf)

{

const union nios2_register *regset = (union nios2_register *) buf;

int i;

for (i = 0; i < nios2_num_regs; i++)

nios2_supply_register (regcache, i, regset + i);

}

static struct regset_info nios2_regsets[] =

{

{ PTRACE_GETREGSET, PTRACE_SETREGSET, NT_PRSTATUS,

nios2_num_regs * 4, GENERAL_REGS,

nios2_fill_gregset, nios2_store_gregset },

NULL_REGSET

};

static struct regsets_info nios2_regsets_info =

{

nios2_regsets, /* regsets */

0, /* num_regsets */

NULL, /* disabled_regsets */

};

static struct usrregs_info nios2_usrregs_info =

{

nios2_num_regs,

nios2_regmap,

};

static struct regs_info regs_info =

{

NULL, /* regset_bitmap */

&nios2_usrregs_info,

&nios2_regsets_info

};

static const struct regs_info *

nios2_regs_info (void)

{

return &regs_info;

}

struct linux_target_ops the_low_target =

{

nios2_arch_setup,

nios2_regs_info,

nios2_cannot_fetch_register,

nios2_cannot_store_register,

NULL,

linux_get_pc_32bit,

linux_set_pc_32bit,

NULL, /* breakpoint_kind_from_pc */

nios2_sw_breakpoint_from_kind,

NULL, /* get_next_pcs */

0,

nios2_breakpoint_at,

};

void

initialize_low_arch (void)

{

init_registers_nios2_linux ();

initialize_regsets_info (&nios2_regsets_info);

}